Common routes for the administration of pharmacologically active agents are a plurality of oral dosage forms, including such familiar forms as tablets, pills, and capsules. Such dosage forms are generally fairly convenient, stable in storage and transport, and familiar to the user. However, they are not without problems, and these problems are often significant. It is extremely difficult for most people to swallow any of these oral dosage forms without supplemental water. In the fast-paced world, it is frequently inconvenient or messy to have to take supplementary water with oral medicaments. Such difficulties are compounded for those with difficulty in swallowing, such as, for example, children and the elderly. Certain medical conditions, such as Parkinsonism or other neurological states, make it difficult to swallow oral dosage forms, even with supplemental water.
Additionally, swallowing oral dosage forms intact implicates a complex system of variables involved in gastrointestinal dissolution of dosage forms and absorption of drugs.
Accordingly, there is considerable interest in oral medicaments and so-called pre-gastric absorption of the active ingredient, that is, absorption of the active ingredient from that part of the alimentary canal prior to the stomach. The term “pre-gastric absorption” thus includes buccal, sublingual, oropharyngeal and esophageal absorption. Medicaments absorbed by such pre-gastric absorption pass straight into the systemic circulatory system thereby avoiding first pass metabolism in the liver. Accordingly, bioavailability of agents absorbed in this way may also be increased. This means that the dose of such agents may be reduced while still producing the desired beneficial effects and this decrease in dose may result in a corresponding reduction of unwanted side effects. Current research, as noted in U.S. Pat. No. 6,110,486 to Dugger, shows in particular that absorption through the buccal mucosa represents an often underappreciated route of oral administration that is unavailable to drugs in tablet, pill, or capsule form. There are also non-oral mucosal absorption sites, such as rectal or vaginal mucosa, that may serve as administration routes for dissolvable medications.
Additionally, a wide range of foodstuffs and oral hygiene products, such as breath fresheners, are obviously orally dispensed. Compositions comprising gelatin are widely used to carry such materials. Gelatin, which is normally utilized in such formulations, is defined as a protein obtained by partial hydrolysis of animal collagenous tissues, such as skins, tendons, ligaments and bones; or various collagenous portions of warm and cold water fish. Thin gelatin strips have been employed, particularly for dispensing breath freshening agents, but these are limited in the amount of active ingredient that can be carried by the thin strips. Much research has been devoted to gelatin capsules that may be broken up in the mouth, and at least partially dissolved by chewing. Gelatin capsules of varying compositions are widely known in the art, but in general, are compounded of various mixtures of gelatin, a plasticizer or plasticizers, and water.
A tension has always existed in the formulation of gelatin capsules, namely, that dosing, stability, and storage and handling characteristics are generally furthered by relatively high gelatin content and a relatively low plasticizer and end water content in the capsules as dispensed; while chewability, mouth feel, and therefore, client acceptance, are generally furthered by lower gelatin content and higher plasticizer and end water contents. With capsules designed to be swallowed intact, generally denominated “hard” gelatin capsules, or soft gel capsules designed to be broken in the mouth and then swallowed, this tension is relatively minor. However, with capsules designed to be broken up in the mouth and completely or nearly completely dissolved by chewing, that is, the so-called “chewable soft” gelatin capsule, this tension is difficult to resolve. Such true “chewable soft” capsules are a type of soft gelatin capsule that is particularly distinguished by both a pleasant chewing experience and a complete or near complete dissolution in a short period of time in the oral cavity. Such capsules are also distinguished by particular fabrication problems, such as excessive stickiness during rotary die encapsulation and sticking of the product to other capsules during post-encapsulation handling. Gelatin capsules with high end water content typically have poor storage performance, sticking to one another in bulk packaging and often melting or leaking during storage.
U.S. Pat. No. 4,935,243 to Borkan, et al. discloses a chewable gelatin capsule composition that comprises less than about 30%, and preferably comprises about 20-26% water, and is directed to the use of a hydrogenated starch hydrolysate, which allowed a lower than expected end water content. U.S. Pat. No. 4,532,126 to Ebert, et al. discloses examples of soft gelatin capsules formed at as high as 37% water content, but specifies that these capsules were then subsequently dried to some undisclosed final end water content, in order to obtain desired chewing characteristics.
U.S. Pat. No. 3,851,051 to Miskel et al. discloses numerous embodiments of a soft gelatin capsule that has an initial capsule shell water content of between 28.3 and 36.6%, but further discloses that the capsules are then dried to be in equilibrium with the internal gel-lattice composition, which has a water content of 15-20%. In U.S. Pat. No. 6,258,380 to Overholt, capsules are fabricated from a wet mass that is initially as much as 30% water by weight, but is then subsequently dried to 6%-8% water.
In addition to the effects of water content, chewability of capsules can be affected by the bloom strength and the melting points of the gelatin used in the encapsulation process. In general, gelatins of lower bloom strength and lower melting point have preferable organoleptic qualities,
Co-owned U.S. Utility patent application Ser. No. 10/456,450 to Makino; accomplished a high degree of hydration using fish gelatin having a low sol-gel transition temperature, that is, a relatively low melting point. However, such formulations can be problematic when stored at high temperatures or high humidity. For example, it is very difficult to formulate a fish gelatin capsule that will be stable at a storage temperature above 35° C. Capsules made with such low melting point gelatins tend to become sticky during storage, and may even burst or melt, releasing their contents. On the other hand, it is known that mammalian gelatins, some of which have melting temperatures above 60° C., tend to be much more stable at higher storage temperatures, but to often have poorer organoleptic qualities. The research behind the instant invention was designed to pursue the goal of increasing heat stability, at least in part by exploring gelatins of higher bloom strength and mammalian origins, while maintaining the excellent organoleptics seen in fish gelatins with low bloom strengths, low melting points, and/or high water contents.
In sum, the art has needed a material and method for the formulation of commercially acceptable chewable gelatin capsules having organoleptic properties similar to those seen with high end water content capsules, that is, capsules having a high water content at the time the capsules are packaged and made available for sale. This is to be accomplished by manipulation of the gelatin, plasticizer, and starch components, while maintaining water levels in the capsules that are within the normal range for such formulations. Additionally, these capsules, which do not have excessively high water contents, should exhibit stability under reasonably expected storage times and conditions.